Project Summary About 6.3% of the US population (ages 12+) have misused prescription (Rx) drugs in the past year, with this prevalence almost double among young adults ages 18-25. Unintentional poisoning deaths involving opioid pain relievers (Rx drugs most likely to be abused) have more than quadrupled from 1999-2010, and now outnumber deaths from heroin and cocaine combined. Deaths related to Rx drug poisoning surpassed motor vehicle crashes as the leading cause of injury-related mortality in 2009. The increase in the use of opioid pain relievers is due in part to the liberalization of laws governing the prescription of opioid analgesics for chronic pain, the introduction of new and more aggressive pain management standards, and the availability of new drugs. This project will estimate the effects of key state initiatives targeting Rx drug abuse. These include mandatory prescription drug monitoring programs (PDMP), an ID requirement at the dispensing stage, and required physical exam of the patient prior to prescribing. For most states participation by prescribers and dispensers in the PDMP is voluntary, and hence PDMP utilization rates are quite low and well below 50%. Furthermore, there is very limited research on the effects of these policies despite recommendations by the Obama administration and many state health departments to institute these programs. In addition to addressing this knowledge gap, this project will also assess whether these policies have had unintended consequences in terms of raising heroin use, which has more than doubled among young adults over the past 5 years. Among illicit drug users, Rx abuse is second in prevalence only to marijuana, and 1 out of 4 new illicit drug users began their habit with non-medical use of Rx drugs. Thus, unintended consequences in the form of greater use of heroin or other illicit drugs may occur as availability of Rx drugs is reduced by state programs. Alternatively, positive spillovers are also possible if the number of individuals who acquire an opioid addiction and consequently transition to heroin or other illicit drugs is reduced. Five complementary data sets will be utilized to investigate these policy effects across a range of self-reported and objectively measured Rx and illicit drug-use and drug-related health outcomes. Considerable variation in the adoption of these initiatives across and within states, including staggered adoption of different policies within the same state, will be exploited within a difference-in-differences (DD) research design to identify credible causal effects. The models will be supplemented with various checks and sensitivity analyses, including testing and adjusting for the assumptions underlying the DD estimation, assessing reinforcement effects across the policies, assessing cumulative effects, assessing cross-border spillovers, and assessing heterogeneous policy responses. The proposed research will provide the most comprehensive study to date of the effectiveness and possible unintended consequences of key state initiatives aimed at curbing Rx drug diversion. These estimates will yield valuable evidence informing policymakers on the mix of regulations effective in reducing Rx abuse.